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Getting Started with Zephyr using BarnOwl on Athena

Using BarnOwl

To start barnowl, run the command athrun barnowl at the
prompt on any Athena machine or ​athena.diaulup.

The simplest use of Zephyr is to send personal zephyrs to other
users. To send a zephyr, type : to bring up a command line, and run
the command zwrite USERNAME. You can also start a zwrite command
by simply typing z.

You can then enter your message, and then enter a . on a line by
itself to finish the zephyr. By convention, zephyrs are usually
word-wrapped to 70-character lines or so; Pressing M-q (Alt-q) will
word-wrap the text you've entered for you.

Once you've sent and received zephyrs, you can navigate the message
list with the arrow keys. Press d to mark a message as deleted,
u to undelete it, and x to expunge all messages that have
been marked as deleted.

Instead of entering a zwrite command manually, you can also select
a message in the message list with the arrow keys, and reply to it
using r, which will automatically set up an appropriate zwrite
command.

For more documentation on the built-in commands and keybindings, you
can press h to bring up barnowl's built-in help screen. For help
with a specific command, bring up a command line with : and then
type help COMMAND.

To quit, type :quit.

Classes and Instances

Most interesting discussion on Zephyr, however, happens on so-called
Zephyr classes. A class is a bit like a chat room in other IM
systems. Anyone can send a zephyr to a class, and anyone who is
subscribed to that class will receive it. There is no security on
classes -- anyone who knows the name of a class can subscribe, and
there is no way to determine who is subscribed to a given class.

To subscribe to a class, use the subscribe command:

:subscribe CLASSNAME * *

To send a zephyr to a class, use the zwrite command with the -c
option:

:zwrite -c CLASSNAME

Zephyrs to classes usually have an instance attached. An instance
is a short “topic” or “subject” that indicates the context of a
zephyr. Different instances are often used to multiplex multiple
conversations on a high-traffic class. You can specify an instance
with the -i option to zwrite:

:zwrite -c CLASSNAME -i INSTANCE

A message without an instance specified will default to the instance
“personal”.

Startup

There might be some options that you want to be consistent from
session to session; you don't want to have to set the same variables
each time. You can fix this by adding the commands to your "startup"
file, for example, .owl/startup. This can be done from within
BarnOwl, by using the startup command:

:startup set foo bar

Where foo is the variable you want to set, and bar is the value.
You do not necessarily have to use the set command, either, any
command you can type in BarnOwl can be added to the startup file.

Logging

It is handy to be able to log your conversations so you can refer back
to them later. To log classes, for example:

:set classlogging on

And to log personals:

:set logging on

This will log to the "zlog" directory in your locker. You probably
don't want people to see what classes you're on or what people you
talk to, so you can run the Athena commands

Note that if you want the logging option to still be set after you
quit and relaunch BarnOwl, you will need to prefix the "set" command
with "startup". This is how you would write that:

:startup set classlogging on
:startup set logging on

See the "Startup" section above for more information.

Persistence

BarnOwl can also be run in a screen session to continue receiving messages while offline.

It can be very annoying to have to close BarnOwl when you turn off
your computer. During the time your computer is off, you're missing
many (possibly important) zephyrs. It can be aggravating to be using
zephyr via an unreliable network connection. It can also be
frustrating if you leave your computer on with Zephyr up, but go to a
different computer and want to check your zephyrs - how do you do
this? These problems can be solved with the magic of screen.

A more detailed and extensive explanation of this can be found at
​http://web.mit.edu/kchen/arch/common/bin/owl-screen.txt. Basic commands are [Ctrl-a] followed by [c] to open a new window (like a tab), [Ctrl-a][w] to see a list of open windows, and [Ctrl-a] followed by a number to go to that window.

Do note that running owl-screen as apposed to just runnning screen and then a barnowl instance provides niceties such as reminders to renew your tickets (the process /mit/kchen/arch/i386_rhel4/bin/cont-renew-notify). Also, BarnOwl will always be located on the 0 tab of an owl-screen instance, so [Ctrl-a][0] will always take you back to BarnOwl.

Screen

You should find a computer or server on which to run your screen
session(s) that is up all the time, for example, linux.mit.edu.
Screen allows you to run programs inside of it on one computer, and to
access those same programs from other computers via ssh.

Quickstart

Pick a machine to host your screen session on.

If you don't know of any options, linux.mit.edu (Linerva) is a good choice.

ssh to that machine.

Run "add kchen". You may want to add this to your ~/.environment file.

Run "owl-screen"

Your screen session is now ready. Once you start the screen session,
you'll need to get renewable Kerberos tickets in order to run it for
any extended period of time. Press C-a C-c to open a new screen
window, and run

kinit -l7d

(length 7 days). Press C-a 0 to return
back to your BarnOwl window.

When you're ready to log out, press C-a d to "detach" your screen, and
then type exit or logout to log out. Later, when you want to
"reattach" your screen, ssh to the machine again, and run screen -r.

Kerberos Tickets and AFS Tokens

In order to keep your screen session authenticated, you'll need to
keep your Kerberos tickets and AFS tokens up-to-date. There is a
script that will do this for you, located in the kchen locker.
After you ssh into the machine that hosts your screen sessions, run
the following commands:

add kchen
owl-screen
C-a C-c
kinit -l1d -r7d

Attaching and Detaching Sessions

To detach a screen session (for example, if you want to log out),
press C-a d (Control-A, then D). Screen continues to run, but is no
longer active.

To reattach a screen session, possibly detaching from wherever it's
currently attached, run: